73 Diamonds-Mid

Diamonds FOCUS Question How do diamonds form?

钻石焦点问题钻石是如何形成的?

What Is a Diamond? Have you ever seen a diamond? It is a beautiful gemstone. Not all diamonds are clear and sparkly, however. Some are dull, They can be brown, gray, or black. They can even be white, yellow, or pink. No matter what color, all diamonds are minerals made of the element carbon. Like many other minerals, diamonds are crystals. Crystals are organized groups of atoms. The shape of a crystal depends on how the atoms are arranged. Most crystals have straight edges and smooth sides. Each side is called a face.

什么是钻石?你见过钻石吗? 这是一种美丽的宝石。 然而，并不是所有的钻石都是透明闪亮的。 有些是暗淡的，他们可以是棕色，灰色，或黑色。 它们甚至可以是白色、黄色或粉色的。 不管什么颜色，所有的钻石都是由碳元素构成的矿物。 像许多其他矿物一样，钻石是晶体。 晶体是有组织的原子群。 晶体的形状取决于原子的排列方式。 大多数晶体有直的边和光滑的边。 每一面都叫脸。

Getting Into Shape Diamond crystals usually have eight faces. Their crystals are octahedrons (ock-tuh-HE-druns). They look like two four-sided pyramids, stuck together bottom to bottom. X-ray pictures help us see how diamonds get their shape. The diagram above shows carbon atoms in a diamond crystal. Compare it to the shape of the diamond. The pattern of atoms in one crystal is the same as the shape of the whole diamond.

钻石晶体通常有八个面。 它们的晶体是八面体(ock-tuh-HE-druns)。 它们看起来像两个四边形的金字塔，从底到底粘在一起。 x射线照片帮助我们了解钻石是如何形成形状的。 上图显示了钻石晶体中的碳原子。 把它和钻石的形状比较一下。 一个晶体中原子的形状和整个钻石的形状是一样的。

A Tale of Two Carbons Diamonds are not the only minerals that are made of carbon. Graphite is also made of pure carbon. Why are diamonds and graphite so different? A bond attaches one atom to another atom. Atoms can bond to each other in different ways. Some bonds are weak. Some are strong. The way a crystal forms affects the strength of bonds that attach atoms together. Diamonds form under very high temperatures and pressure. Diamonds have very strong bonds.

钻石并不是唯一一种由碳组成的矿物。 石墨也是由纯碳构成的。 为什么钻石和石墨如此不同? 键把一个原子连接到另一个原子上。 原子可以以不同的方式相互结合。 有些债券很弱。有些人很强壮。 晶体的形成方式会影响原子间化学键的强度。 钻石在非常高的温度和压力下形成。 钻石有很强的化学键。

Graphite forms under much lower temperatures and pressure than diamonds do. The bonds that attach the carbon atoms in graphite crystals are much weaker. This makes graphite soft and slippery. These properties make graphite good for use in pencils. Science in Your World The "lead" in your pencil is actually graphite. Graphite has been used for writing since the 16th century. The Englishmen who began using it thought graphite was lead.

石墨形成的温度和压力比钻石低得多。 石墨晶体中连接碳原子的化学键要弱得多。 这使得石墨又软又滑。 这些特性使得石墨很适合用来做铅笔。 你铅笔里的“铅”实际上是石墨。 石墨自16世纪以来就被用于书写。 开始使用石墨的英国人认为石墨就是铅。

Super Crystals! Earth's outer layer is the crust. Under it is the mantle. Diamonds form in the mantle, about 160 kilometers (100 mi.) below Earth's surface There, rock is under a lot of pressure because of the heavy rock above it It is also very hot. It is so hot in Earth's mantle that some of the rock melts and turns into magma. Diamonds form as magma cools and turns back into solid rock. If the magma cools slowly, the diamond crystal grows bigger. This happens because there is more time for carbon atoms to bond together. If the magma cools quickly, crystals do not have as much time to form The diamonds are smaller.

超级水晶!地球的外层是地壳。 在它下面是地幔。钻石形成于地球表面以下约160公里(100英里)的地幔中。在那里，岩石承受着很大的压力，因为上面的岩石很重。 地幔中温度极高，一些岩石融化变成岩浆。 钻石是在岩浆冷却后重新变成坚硬的岩石时形成的。 如果岩浆慢慢冷却，钻石晶体就会变大。 这是因为碳原子有更多的时间结合在一起。 如果岩浆迅速冷却，晶体就没有那么多时间形成。钻石就变小了。